1. Field of the Invention
The present invention relates to a mono-component developing apparatus and a developing roller to be used in such a developing apparatus. In particular, the developing roller of the present invention is classified as a hard roller without a foamed material layer.
2. Description of the Related Art
In a mono-component developing apparatus, an electrostatic latent image on a latent-image-bearing member is visualized by using a mono-component developer made from toner, through an electro-photographic system. In a two-component developing apparatus, an electrostatic latent image is visualized by using a two-component developer made from toner and a carrier. In the mono-component developing apparatus, upon transporting the toner to a developing area by the rotation of the developing roller, different from the two-component developing apparatus, no magnetic force can be utilized, and since the toner is not sufficiently held, a problem arises in which toner leakage occurs due to toner movements toward the developing-roller axis direction.
In order to prevent the toner leakage in the mono-component developing apparatus, as shown in FIG. 6, a technique has been known in which a developing roller 100 is allowed to rotate while frictionally sliding on a sealing member 101 on each of the two end portions. In this technique, the frictionally sliding area on the sealing member on each of the two end portions of the developing roller 100 is evenly subjected to the same treatment as that of the toner supporting area in the center portion, and, for example, a blasting treatment or a coating treatment is evenly carried out over the entire frictionally sliding area. However, toner is intruded into a gap between each of the two end portions of the developing roller and the sealing member to cause toner fusion, failing to sufficiently prevent toner leakage.
In order to solve this problem, with respect to the developing roller in which the metal core shaft is coated with resin, a structure in which the sliding area on the sealing member on each of the two end portions is not resin-coated has been proposed (Japanese Patent Application Laid-Open No. 2003-186299). With this arrangement, the intrusion of toner between the developing roller and the sealing member can be prevented so that it becomes possible to prevent toner leakage.
However, in the above-mentioned developing roller, since the adhesion between the developing roller and the sealing member become high, a new problem is raised in which the driving torque of the developing roller is raised extremely.